JP5582406B2 - High frequency dielectric ceramic composition and manufacturing method thereof, high frequency dielectric ceramic and manufacturing method thereof, and high frequency circuit element using the same - Google Patents

Description

The present invention relates to a dielectric ceramic composition for high frequency use, and in particular, has a relative dielectric constant ε _r of 7.5 to 12.0 and Q _m × f. The value is sufficiently large, and the resonance frequency f. The absolute value of temperature coefficient (tau) _f of this is related with the dielectric ceramic composition for high frequencies whose 30 ppm / degrees C or less. The present invention also relates to a method for producing a high frequency dielectric ceramic composition as described above.

  Furthermore, the present invention relates to a high frequency dielectric ceramic suitable as a member constituting a high frequency circuit element used in a high frequency region such as a microwave and a millimeter wave. Examples of such high-frequency dielectric ceramics are used in dielectric blocks, dielectric substrates, and various high-frequency circuit elements, which are components such as dielectric resonators, dielectric waveguides, and dielectric antennas. And a substrate and a supporting member. The high-frequency circuit element constitutes an electronic device such as a communication device in a high-frequency range, for example.

In recent years, with the rapid development of communication networks, the frequency used for communication has expanded to the high frequency region of the microwave region and the millimeter wave region. As a dielectric ceramic composition used for producing such an electronic component for a high-frequency circuit (high-frequency electronic component), the material has a large loss factor Q _m (sometimes simply referred to as Q), Furthermore, the resonance frequency f. There is a need for a material that has a small absolute value of the temperature coefficient τ _f and can be easily adjusted to a desired value.

As the relative dielectric constant ε _r of the high frequency dielectric ceramic composition increases, the size of the high frequency electronic component constituting the high frequency circuit such as a microwave circuit or a millimeter wave circuit can be reduced. However, in the high frequency region of microwave and millimeter wave, if the dielectric constant ε _{r of the} dielectric ceramic composition used for the high frequency electronic component is too large, the size of the high frequency electronic component becomes too small and the processing accuracy is too high. Productivity decreases because it becomes severe. For this reason, the relative dielectric constant ε _r of the high frequency dielectric ceramic composition is required to be moderate. In addition, because the size of high-frequency electronic components varies depending on the frequency used, high-frequency electronics for high-frequency circuits such as microwave circuits and millimeter-wave circuits that have both the features of improved workability and miniaturization. In order to realize the component, it is desirable that the material of the high-frequency electronic component can easily obtain the required relative dielectric constant ε _r (that is, can be adjusted).

Conventionally, BaO—MgO—WO ₃ -based materials (see Patent Document 1), MgTiO ₃ —CaTiO ₃ -based materials (see Patent Document 2), and the like have been proposed as high-frequency dielectric ceramic compositions. However, all of these high frequency dielectric ceramic compositions have a relative dielectric constant ε _r of 13 or more, and have a lower relative dielectric constant ε _r as the operating frequency is increased. Is required. Further, in these high frequency dielectric ceramic compositions, the relative permittivity ε _r is _limited to a relatively narrow range in the composition region where the absolute value of the temperature coefficient τ _f of the resonance frequency exhibits a characteristic around 0 ppm / ° C. There was a problem that it could not be adjusted.

On the other hand, alumina (Al ₂ O ₃ ), forsterite (Mg ₂ SiO ₄ ), cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ) and the like have excellent Q _m values and are used for electronic circuit boards and the like. Yes. However, since the temperature coefficient τ _f of the resonance frequency is −30 to −70 ppm / ° C., the application is limited. Moreover, when these materials are mixed with impurities, there are problems such as having a great influence on the generated phase and electrical characteristics.

Furthermore, a porcelain composition (see Patent Document 3) composed of forsterite (Mg ₂ SiO ₄ ), calcium titanate (CaTiO ₃ ), and spinel has been proposed. However, although Patent Document 3 discloses that the temperature dependence of the relative permittivity ε _r of the porcelain composition is controlled, the value of the relative permittivity ε _r and the possibility of control or adjustment thereof. Is not disclosed at all.

Further, a dielectric ceramic composition (see Non-Patent Document 1) in which titanium oxide (TiO ₂ ) is added to forsterite (Mg ₂ SiO ₄ ) has been proposed. However, in this dielectric ceramic composition, although the temperature coefficient τ _{f of the} resonance frequency is gradually shifted to the positive side with the addition of titanium oxide (TiO ₂ ), the temperature coefficient τ of the resonance frequency is added even when 30 wt% of titanium oxide is added. _{Since f} is a negative and large value of −62 ppm / ° C., it is not practical.

  By the way, the most basic one of the dielectric resonators is a coaxial dielectric resonator. In this coaxial dielectric resonator, a through-hole is provided in a block made of dielectric ceramic, and only one surface (open surface) of the block in which the through-hole opens is left as it is. A conductor film is formed on the surface and the inner surface of the through hole.

  A microstrip line is the most basic dielectric waveguide that is a planar high-frequency circuit element. In this microstrip line, a strip conductor is provided on one of the front and back surfaces of the dielectric ceramic substrate, and a ground conductor film is provided on the other surface of the dielectric ceramic substrate.

  A dielectric resonator control type microwave transmitter can be configured using the above coaxial dielectric resonator and microstrip line. In this microwave oscillator, a coaxial dielectric resonator is attached to a dielectric ceramic substrate via a support member made of a dielectric ceramic, and an electromagnetic field leaking out of the coaxial dielectric resonator is utilized. The resonator is coupled to the microstrip line provided on the dielectric ceramic substrate.

In this type of high-frequency circuit, a resonance system with a high unloaded Q is configured by suppressing the electric field from leaking through the support member. Therefore, it is necessary to use a material for the support member that has a low relative dielectric constant and a low dielectric loss (tan δ) (that is, a large Q _m × f). For this reason, conventionally, as a material of the support member, the relative dielectric constant εr is about 7, and Q _m × f. Was forsterite (Mg ₂ SiO ₄ ) of about 150,000 GHz. As a material for the dielectric ceramic substrate, the relative dielectric constant εr is mainly about 10 and Q _m × f. Has been adopted alumina ceramics (Al ₂ O ₃ ) of 200000 GHz or more (for example, see Patent Document 4). However, in these materials, the temperature coefficient τ _f of the resonance frequency tends to be −30 to −70 ppm / ° C., so that the use of the high frequency circuit is limited. In addition, when these materials are mixed with impurities, there is a problem that the structure of the generated phase and the electrical characteristics greatly vary.

  Moreover, the dielectric ceramic based on the dielectric ceramic composition described in Non-Patent Document 1 is not practical.

On the other hand, Teflon (registered trademark) and alumina porcelain (Al ₂ O ₃ ) are generally used as materials for the dielectric ceramic substrate constituting the dielectric waveguide. However, since these materials tend to have a temperature coefficient τ _f of the resonance frequency of −30 to −70 ppm / ° C., the use of the high frequency circuit is limited.

Further, the relative dielectric constant ε _r = 24, Q _m × f. There is a development example (Non-patent Document 2) in which a dielectric having a temperature coefficient of τ _f = 0 ppm / ° C. is applied to a planar filter (Non-patent Document 2), but in order to meet the demand for further higher frequency in the future The relative dielectric constant ε _r is about 12 or less and Q _m × f. Is 40000 GHz or more, preferably 50000 GHz or more, and the resonance frequency f. It is necessary that the absolute value of the temperature coefficient τ _f is 30 ppm / ° C. or less.

  Further, the higher the frequency region, the greater the influence of the skin effect. For example, when Ag is used as the conductor, the skin depth is 1.18 to 2.04 μm in the region of 1 to 3 GHz (non-patented). Reference 3).

Japanese Patent Laid-Open No. 6-236708 (see paragraph number (0033) on page 11, Tables 1 to 8) Japanese Unexamined Patent Publication No. Hei 6-199568 (see paragraph number (0018) on page 5, Tables 1 to 3) JP 2000-344571 (see paragraph number (0006) on the second page) JP-A-62-103904

Journal of the European Ceramic Society (Vol. 23 (2003), page 2575, see Table 3) A Ka-band Diplexer Using Planar TE Mode Dielectric Resonators with Plastic Package (Metamorphosis, No. 6, pp. 38-39 (2001)) Science chronology 2007 edition

In view of the technical problems of the conventional high-frequency dielectric ceramic composition as described above, one object of the present invention is that the relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value is sufficiently large, and the resonance frequency f. It is an object to provide a dielectric ceramic composition for high frequency in which the absolute value of the temperature coefficient τ _f is 30 ppm / ° C. or less.

  Another object of the present invention is to provide a method for producing such a high frequency dielectric ceramic composition.

  Further, in view of the technical problems of the conventional high-frequency dielectric ceramics as described above, the present inventors have made the composition of the dielectric ceramics appropriate and the relative density of the dielectric ceramics. It was found that by making it appropriate, the electrical characteristics in the high-frequency region were excellent and the manufacturing was easy. And this invention is made | formed based on this knowledge.

  That is, an object of the present invention is to provide a high-frequency dielectric ceramic having excellent electrical characteristics in a high-frequency region and easy to manufacture, and a method for manufacturing the same.

  Another object of the present invention is to provide a high-frequency circuit element using such a high-frequency dielectric ceramic as a constituent member.

  Further, in view of the technical problems of the conventional high-frequency dielectric ceramics as described above, the present inventors have made the composition of the dielectric ceramics appropriate, and the surface roughness of the dielectric ceramics. It was found that the electrical characteristics in the high-frequency region would be excellent by making the values appropriate. And this invention is made | formed based on this knowledge.

  That is, an object of the present invention is to provide a high frequency dielectric ceramic excellent in electrical characteristics in a high frequency region and a method for manufacturing the same.

  Another object of the present invention is to provide a high-frequency circuit element using such a high-frequency dielectric ceramic as a constituent member.

(1) First invention:
According to the present invention, to achieve any of the above objects,
Represented by the composition formula a (Sn, Ti) O ₂ —bMg ₂ SiO ₄ —cMgTi ₂ O ₅ —dMgSiO ₃ , and a, b, c, and d (where a, b, c, and d in the composition formula) Is in a range of 4 ≦ a ≦ 37, 34 ≦ b ≦ 92, 2 ≦ c ≦ 15, and 2 ≦ d ≦ 15, respectively, where a + b + c + d = 100 Composition,
Is provided.

In one embodiment of the present invention, the (Sn, Ti) O ₂ is (Sn _0.8 Ti _0.2 ) O ₂ .

In addition, according to the present invention, to achieve any of the above objects,
A method for producing the above-mentioned high frequency dielectric ceramic composition, using SnO ₂ , TiO ₂ and Mg ₂ SiO ₄ as starting materials, and mixing and crushing a predetermined amount of these starting materials A method for producing a dielectric ceramic composition for high frequency, characterized in that a binder is added to be molded and fired,
Is provided.

(2) Second invention:
In addition, according to the present invention, to achieve any of the above objects,
A main component comprising the high frequency dielectric ceramic composition, and an additive component comprising MnO, wherein the additive component is added in an amount of 0.1 to 5.0 parts by weight per 100 parts by weight of the main component. A dielectric ceramic for high frequency, wherein the relative density is 95% or more,
Is provided.

In one aspect of the present invention, the high frequency dielectric ceramic has a relative dielectric constant ε _r of 7.5 to 12.0 and Q _m × f. The value is 40000 or more, preferably 50000 or more, and the resonance frequency f. Has a temperature coefficient τ _f of −30 to +30 ppm / ° C.

In addition, according to the present invention, to achieve any of the above objects,
A method for producing the above-mentioned dielectric ceramic for high frequency, wherein a predetermined amount of SnO ₂ , TiO ₂ and Mg ₂ SiO ₄ is mixed and calcined and then pulverized as a starting material, and 100 parts by weight of the starting material An organic binder is added to a powder obtained by adding 0.1 to 5.0 parts by weight of MnO as a sintering aid to the powder, and the resulting product is fired. Production method,
Is provided.

  In addition, according to the present invention, there is provided a high-frequency circuit element characterized by including a member made of the above-described high-frequency dielectric porcelain, in order to achieve any of the above objects.

(3) Third invention:
In addition, according to the present invention, to achieve any of the above objects,
The dielectric ceramic for high frequency, comprising the dielectric ceramic composition for high frequency, and having an arithmetic mean roughness Ra of 2 μm or less on the surface,
Is provided.

In one aspect of the present invention, the high frequency dielectric ceramic has a relative dielectric constant ε _r of 7.5 to 12.0 and Q _m × f. The value is 40000 or more, preferably 50000 or more, and the resonance frequency f. Has a temperature coefficient τ _f of −30 to +30 ppm / ° C.

In addition, according to the present invention, to achieve any of the above objects,
A method of manufacturing the above dielectric ceramic for high frequency, using SnO ₂ , TiO ₂ and Mg ₂ SiO ₄ as starting materials, and mixing a predetermined amount of these starting materials so that the D50 of the particle size distribution is 2 μm or less. A method for producing a dielectric ceramic for high frequency, characterized by adding a binder to the powder obtained by pulverization, shaping, and firing.
Is provided.

  In addition, according to the present invention, there is provided a high-frequency circuit element characterized by including a member made of the above-described high-frequency dielectric porcelain, in order to achieve any of the above objects.

According to the present invention, the relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value of _{(Q m f., Qf.} , Q m f, Qf, Q × f., Q m × f, and Q × It is to be abbreviated as f or the like) is sufficiently large, further resonance frequency f. High frequency dielectric ceramic composition the absolute value of the temperature coefficient tau _f is not more than 30 ppm / ° C. is provided. By using this high-frequency dielectric ceramic composition, it is easy to provide a high-frequency dielectric ceramic electronic component having good characteristics and features of both improved workability and downsizing.

In addition, according to the present invention, a high frequency dielectric ceramic having excellent electrical characteristics in a high frequency region and easy to manufacture is provided. In particular, the relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value is sufficiently large, and the resonance frequency f. An absolute value of the temperature coefficient τ _f of the high frequency dielectric ceramic is 30 ppm / ° C. or less, and can be fired at a relatively low temperature. By using this high-frequency dielectric ceramic as a constituent member, a high-frequency circuit element having excellent characteristics, both good workability and ease of miniaturization is provided.

In addition, according to the present invention, a high frequency dielectric ceramic having excellent electrical characteristics in a high frequency region is provided, and in particular, the relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value is sufficiently large, and the resonance frequency f. A high frequency dielectric ceramic having an absolute value of the temperature coefficient τ _f of 30 ppm / ° C. or less is provided. By using this high-frequency dielectric ceramic as a constituent member, a high-frequency circuit element having excellent characteristics, both good workability and ease of miniaturization is provided.

1 is an X-ray diffraction diagram of a high frequency dielectric ceramic composition of the present invention. It is an EDS analysis figure of the dielectric ceramic composition for high frequency of the present invention. 1 is a schematic perspective view of a coaxial dielectric resonator that is an example of a high-frequency circuit device manufactured using the high-frequency dielectric ceramic composition of the present invention. It is a typical sectional view of a dielectric resonator control type microwave transmitter which is an example of a high frequency circuit element. It is a typical perspective view of the microstrip line which is an example of a high frequency circuit element. It is a typical top view which shows the pattern of the various microstrip line | wires which comprise a planar high frequency circuit element. FIG. 3 is an X-ray diffraction diagram of a high frequency dielectric ceramic according to the present invention. It is a figure which shows an example of the particle size distribution of the raw material mixture used for manufacture of the dielectric ceramic for high frequencies of this invention. FIG. 3 is an X-ray diffraction diagram of a high frequency dielectric ceramic according to the present invention.

The high frequency dielectric ceramic composition of the present invention is represented by a composition formula a (Sn, Ti) O ₂ -bMg ₂ SiO ₄ -cMgTi ₂ O ₅ -dMgSiO ₃ , and a, b, c in the composition formula, and d (where a, b, c, and d are mol%) are in the range of 4 ≦ a ≦ 37, 34 ≦ b ≦ 92, 2 ≦ c ≦ 15, and 2 ≦ d ≦ 15, respectively. Here, a + b + c + d = 100.

As shown in the X-ray diffraction diagram of FIG. 1, the dielectric ceramic composition for high frequency of the present invention is particularly tin titanate ((Sn, Ti) O ₂ ), forsterite (Mg ₂ SiO ₄ ), magnesium. Titanate (MgTi ₂ O ₅ ) and steatite (MgSiO ₃ ) are the main production phases. As the (Sn, Ti) O ₂ , (Sn _0.8 Ti _0.2 ) O ₂ and (Sn _0.2 Ti _0.8 ) O ₂ are known. Among these, (Sn _0.8 Ti _0.2 ) O ₂ has characteristics that it is easier to sinter and more easily controls τ _f than (Sn _0.2 Ti _0.8 ) O ₂ .

The dielectric ceramic composition for high frequency of the present invention is Q _m × f. Since the value is as high as 40,000 (GHz) or higher, for example, about 50,000 to 80,000 (GHz), it is easy to provide a high frequency dielectric ceramic having a very low dielectric loss and an electronic component using the same. In addition, since the absolute value of the temperature coefficient τ _f of the resonance frequency is 30 ppm / ° C. or less, the high-frequency dielectric ceramic composition of the present invention has a high-frequency dielectric ceramic with little influence on characteristics due to temperature, and the It becomes easy to provide the used electronic components. Moreover, since the dielectric ceramic composition for high frequency of the present invention has a relative dielectric constant ε _r of 7.5 to 12.0, the dielectric for high frequency having both features of improved workability and downsizing. The provision of the body porcelain electronic parts is facilitated.

The reason for limiting the composition of the high frequency dielectric ceramic composition of the present invention will be described. In the composition formula a (Sn, Ti) O ₂ —bMg ₂ SiO ₄ —cMgTi ₂ O ₅ —dMgSiO ₃ , if a is less than 4, the temperature coefficient τ _f of the resonance frequency is smaller than −30 ppm / ° C. (that is, the temperature The absolute value of the coefficient τ _f is larger than 30 ppm / ° C.), which is not preferable. When a exceeds 37, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. A more preferable range of a is 18 ≦ a ≦ 36. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If b is less than 34, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If b exceeds 92, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. A more preferable range of b is 34 ≦ b ≦ 68. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If c is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. When c exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If d is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. If d exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable.

As shown in Examples described later, the resonance frequency f is obtained by appropriately changing the molar ratios a, b, c, and d in the composition formula within the composition range in the high frequency dielectric ceramic composition of the present invention. The absolute value of the temperature coefficient τ _f is 30 ppm / ° C. or less, that is, sufficiently large Q _m × f within a range where τ _f is close to zero. It is possible to adjust the relative dielectric constant εr to a desired value in the range of 7.5 to 12.0 while realizing the value.

Next, a method for producing the high frequency dielectric ceramic composition of the present invention will be described. The most preferable method for producing the high frequency dielectric ceramic composition of the present invention is a method using tin oxide (SnO ₂ ), titanium oxide (TiO ₂ ), and forsterite (Mg ₂ SiO ₄ ) as starting materials. By firing these together, the target composition, that is, (Sn, Ti) O ₂ , Mg ₂ SiO ₄ , MgTi ₂ O ₅ , and MgSiO ₃ is represented by the above composition formula as the main product phase. Can be obtained.

One embodiment of the method for producing a high frequency dielectric ceramic composition of the present invention is as follows. A predetermined amount of starting materials of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ are wet mixed together with a solvent such as alcohol. Subsequently, the solvent is removed and then pulverized. The powder thus obtained is mixed with an organic binder such as polyvinyl alcohol to make it homogeneous, followed by drying, crushing, and pressure molding (pressure of about 100 to 1000 kg / cm ² ). By firing the obtained molded product at 1200 to 1450 ° C. in an oxygen-containing gas atmosphere such as air, a high frequency dielectric ceramic composition represented by the above composition formula can be obtained.

As shown in the examples described below, equimolar amounts of SnO ₂ and TiO ₂ can be used. In this case, in particular, the generated phase (Sn, Ti) O ₂ is preferably (Sn _0.8 Ti _0.2 ) O ₂ .

  The high-frequency dielectric ceramic composition (including those in the form of porcelain) thus obtained is processed into an appropriate shape and size as necessary, so that a high-frequency dielectric ceramic such as a dielectric resonator can be obtained. Can be used as an electronic component. In particular, by forming a film or wiring made of a conductor such as silver or copper on the outside, it can be used as a high frequency dielectric ceramic electronic component such as a so-called coaxial resonator or a coaxial dielectric filter using the same. Is possible. Furthermore, it can be used as a dielectric wiring board as a dielectric ceramic electronic component for high frequency by processing into a plate shape and forming a conductor wiring such as silver or copper. Further, the powdery dielectric ceramic composition for high frequency of the present invention is mixed with a binder resin such as polyvinyl butyral, a plasticizer such as dibutyl phthalate, and an organic solvent such as toluene, and sheet molding by a doctor blade method or the like is performed. By stacking the obtained sheet and the conductor sheet and firing them together, it can be used as a laminated high frequency dielectric ceramic electronic component such as a laminated dielectric filter or a laminated dielectric wiring board. Can do.

In addition to SnO ₂ , MgO, SiO ₂ , TiO ₂ , and the like as raw materials for tin, magnesium, silicon, and titanium, which are elements constituting the high frequency dielectric ceramic composition of the present invention, oxidation is performed during firing. Nitrate, carbonate, hydroxide, chloride, organometallic compound, and the like can be used.

The main component of the high frequency dielectric ceramic of the present invention is composed of the above high frequency dielectric ceramic composition, that is, the composition formula a (Sn, Ti) O ₂ -bMg ₂ SiO ₄ -cMgTi ₂ O ₅ -dMgSiO ₃ . A, b, c, and d (where a, b, c, and d are mol%) in the composition formula are 4 ≦ a ≦ 37, 34 ≦ b ≦ 92, and 2 ≦ c ≦, respectively. 15 and 2 ≦ d ≦ 15, where a + b + c + d = 100. The additive component of the high frequency dielectric ceramic of the present invention is made of MnO. This additive component is added in an amount of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the main component.

As shown in the X-ray diffraction diagram of FIG. 7, the high-frequency dielectric ceramic according to the present invention has tin titanate ((Sn, Ti) O ₂ ), forsterite (Mg ₂ SiO ₄ ), magnesium titanate ( MgTi ₂ O ₅ ) and steatite (MgSiO ₃ ) are the main production phases. As the (Sn, Ti) O ₂ , (Sn _0.8 Ti _0.2 ) O ₂ and (Sn _0.2 Ti _0.8 ) O ₂ are known. Among these, (Sn _0.8 Ti _0.2 ) O ₂ has characteristics that it is easier to sinter and more easily controls τ _f than (Sn _0.2 Ti _0.8 ) O ₂ . FIG. 7 shows only the main product phase and does not appear because the additive component MnO is very small.

The dielectric ceramic for high frequency of the present invention is Q _m × f. Shows a high value of 40,000 GHz or more, for example, 50000 GHz or more, it is easy to provide a high frequency dielectric ceramic having a very low dielectric loss and a high frequency circuit element using the same. In addition, the high frequency dielectric ceramic according to the present invention uses a high frequency dielectric ceramic that has little influence on characteristics due to temperature since the absolute value of the temperature coefficient τ _f of the resonance frequency is 30 ppm / ° C. or less. Provision of a high-frequency circuit element is facilitated. In addition, since the dielectric ceramic for high frequency according to the present invention has a relative dielectric constant ε _r of 7.5 to 12.0, a high frequency circuit element having both features of improved workability and downsizing is provided. Becomes easier.

Furthermore, in the high frequency dielectric ceramic of the present invention, the additive component MnO is added in an amount of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the main component and the relative density is 95% or more. Q _m × f. , Τ _f and ε _r have good characteristics, and are manufactured at a high yield without reacting with a base plate made of zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ) or the like that comes into contact during firing during production. Accordingly, it is easy to provide a high-frequency circuit element. An example of such a high frequency circuit element is a coaxial dielectric resonator as shown in FIG. Here, a block in which a cylindrical through hole having a hole diameter of 3 mm is provided along the axial length direction in a block of a dielectric ceramic having an outer dimension of 10.6 mm × 10.6 mm × 12 mm (axial length), and the through hole is opened. Only one surface (open surface) of the dielectric ceramic is left as it is (ceramic surface), and a conductor film made of an Ag conductor is formed on the other surface of the dielectric ceramic and the inner surface of the through hole.

The reason for limiting the composition of the high frequency dielectric ceramic according to the present invention will be described. In the main component composition formula a (Sn, Ti) O ₂ -bMg ₂ SiO ₄ -cMgTi ₂ O ₅ -dMgSiO ₃ , if a is less than 4, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. ( That is, the absolute value of the temperature coefficient τ _f is greater than 30 ppm / ° C.), which is not preferable. When a exceeds 37, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. A more preferable range of a is 18 ≦ a ≦ 36. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If b is less than 34, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If b exceeds 92, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. A more preferable range of b is 34 ≦ b ≦ 68. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If c is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. When c exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If d is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. If d exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable.

As shown in the examples described later, the resonance frequency f is obtained by appropriately changing the molar ratios a, b, c, and d in the composition formula of the main component within the composition range in the high frequency dielectric ceramic of the present invention. The absolute value of the temperature coefficient τ _f is 30 ppm / ° C. or less, that is, a desired value in the range of 7.5 to 12.0 is achieved while the dielectric constant ε r is in the range of 7.5 to 12.0 while realizing a sufficiently large Q _m value in the range where τ _f is close to zero It is possible to adjust to.

In addition, when the amount of the additive component MnO added to 100 parts by weight of the main component is less than 0.1 parts by weight, it is difficult to achieve a relative density of 95% or more by firing at a relatively low temperature of 1300 ° C. or less, particularly 1250 ° C. or less. Q _m × f. Since it becomes difficult to obtain a value, it is not preferable. On the other hand, when the addition amount of the additive component MnO with respect to 100 parts by weight of the main component exceeds 5.0 parts by weight, good Q _m × f. It is difficult to obtain the value and ε _r , and further, it reacts with the base plate that is in contact during firing during production, and the production yield tends to decrease, which is not preferable.

An embodiment of the method for manufacturing a high frequency dielectric ceramic according to the present invention is as follows. SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ are wet-mixed in predetermined amounts together with a solvent such as alcohol. Subsequently, after removing the solvent, it is calcined at 1000 to 1150 ° C. and pulverized to obtain a starting raw material powder.

A predetermined amount of MnO as a sintering aid is added to this starting material powder and wet mixed with a solvent such as alcohol. Subsequently, an organic binder such as polyvinyl alcohol is added to the powder obtained by removing the solvent, and after mixing, homogenizing, drying and crushing, the molding density is preferably 2.0 to 2.4 g / cm ³ , preferably Is pressure-molded so as to be 2.2 to 2.4 g / cm ³ . The obtained molded product is fired at 1200 to 1300 ° C. in an oxygen-containing gas atmosphere such as air, thereby containing a main component represented by the above composition formula and an additive component composed of MnO. 0.1 to 5.0 parts by weight are added to 100 parts by weight of the component, and a high frequency dielectric ceramic having a relative density of 95% or more can be obtained.

As shown in the examples described below, equimolar amounts of SnO ₂ and TiO ₂ can be used. In this case, in particular, the generated phase (Sn, Ti) O ₂ is preferably (Sn _0.8 Ti _0.2 ) O ₂ .

  The high-frequency dielectric ceramic thus obtained can be processed into an appropriate shape and size if necessary.

  The high frequency dielectric porcelain of the present invention is formed, for example, by forming a film or wiring made of a conductor such as silver or copper on the outside, thereby forming a coaxial dielectric resonator as shown in FIG. 3 or a coaxial type using the same. It can be used to construct a high-frequency circuit element such as a dielectric filter. The plate-shaped high frequency dielectric ceramic of the present invention can be used as a dielectric wiring board for various high frequency circuits by forming a conductor wiring such as silver or copper.

  Also, add a predetermined amount of MnO as a sintering aid to the starting raw material powder, add a low melting glass, and then mix with a binder resin such as polyvinyl butyral, a plasticizer such as dibutyl phthalate, and an organic solvent such as toluene. A laminated high frequency circuit element such as a laminated dielectric filter or a laminated dielectric wiring board is obtained by forming a sheet by a doctor blade method, etc., laminating the obtained sheet and a conductor sheet, and firing them integrally. Can be obtained.

In addition to SnO ₂ , TiO ₂ , Mg ₂ SiO ₄ , and MnO, SnO, Mg, Si, and Ti, which are elements constituting the high frequency dielectric ceramic according to the present invention, may be made of MgO, An oxide such as SiO ₂ can also be used, and nitrates, carbonates, hydroxides, chlorides, organometallic compounds, and the like that become oxides during firing can also be used.

  The high-frequency dielectric ceramic of the present invention has O, Sn, Mg, Si, and Ti, and MnO as its constituent elements. For example, Ca, Ba, Zr, Ni, Fe, Cr, P, Na, etc. may be mixed as impurities.

The high frequency dielectric ceramic of the present invention, as long as the low dielectric constant and a high Q _m value is determined, can be used as components of various high-frequency circuit device. One example is a component in a dielectric resonator-controlled microwave transmitter as shown in FIG. In this microwave oscillator, a coaxial dielectric resonator 1 is attached to a dielectric ceramic substrate 3 via a support member 2 made of a dielectric ceramic, and an electromagnetic field H leaking out of the coaxial dielectric resonator 1 is used. Thus, the coaxial dielectric resonator 1 and the microstrip line strip conductor 4 provided on the dielectric ceramic substrate 3 are coupled. Reference numeral 5 denotes a metal case that exhibits an electromagnetic shielding function. In this microwave oscillator, the high frequency dielectric ceramic according to the present invention is used as a dielectric block of the coaxial dielectric resonator 1 as described with reference to FIG. 3 as a support member 2 and further as a dielectric ceramic substrate 3. Each can be used. FIG. 5 shows details of the microstrip line. In the microstrip line, the strip conductor 7 is provided on the surface of the dielectric ceramic substrate 6 (corresponding to the dielectric ceramic substrate 3), and the ground conductor film 8 is provided on the back surface of the dielectric ceramic substrate 6. Examples of the material of the strip conductor 7 include Pd, Cu, Au, and Ag.

  Other examples of the high-frequency circuit element in which the high-frequency dielectric ceramic of the present invention is used as a constituent member include planar high-frequency circuit elements as shown in FIGS. 6A to 6I, respectively. These planar high-frequency circuit elements 9 are provided with a strip conductor 7 on the surface of the dielectric ceramic substrate 6 and a ground conductor film on the back surface of the dielectric ceramic substrate 6 in the same manner as the microstrip line. Various patterns of conductive films are formed on the surface of the dielectric ceramic substrate 6 with the same material as that of the strip conductors 7, and the functions of the respective elements are exhibited by the conductive films. In FIG. 6, the element (a) is an interdigital capacitor, the element (b) is a spiral inductor, the element (c) is a branch circuit, and the element (d) is a directional coupler. The element (e) is a power distribution synthesizer, the element (f) is a low-pass filter, the element (g) is a band-pass filter, and the element (h) is a ring resonator. , (I) is a patch antenna.

Another high-frequency dielectric ceramic according to the present invention is composed of the above-described high-frequency dielectric ceramic composition, that is, represented by the composition formula a (Sn, Ti) O ₂ -bMg ₂ SiO ₄ -cMgTi ₂ O ₅ -dMgSiO ₃ . A, b, c, and d (wherein a, b, c, and d are mol%) in the composition formula are 4 ≦ a ≦ 37, 34 ≦ b ≦ 92, and 2 ≦ c ≦ 15, respectively. , And 2 ≦ d ≦ 15, where a + b + c + d = 100.

As shown in the X-ray diffraction diagram of FIG. 9, the high-frequency dielectric ceramic of the present invention has tin titanate ((Sn, Ti) O ₂ ), forsterite (Mg ₂ SiO ₄ ), magnesium titanate ( MgTi ₂ O ₅ ) and steatite (MgSiO ₃ ) are the main production phases. As the (Sn, Ti) O ₂ , (Sn _0.8 Ti _0.2 ) O ₂ and (Sn _0.2 Ti _0.8 ) O ₂ are known. Among these, (Sn _0.8 Ti _0.2 ) O ₂ has characteristics that it is easier to sinter and more easily controls τ _f than (Sn _0.2 Ti _0.8 ) O ₂ .

The dielectric ceramic for high frequency of the present invention is Q _m × f. Shows a high value of 40,000 GHz or more, for example, 50000 GHz or more, it is easy to provide a high frequency dielectric ceramic having a very low dielectric loss and a high frequency circuit element using the same. In addition, the high frequency dielectric ceramic according to the present invention uses a high frequency dielectric ceramic that has little influence on characteristics due to temperature since the absolute value of the temperature coefficient τ _f of the resonance frequency is 30 ppm / ° C. or less. Provision of a high-frequency circuit element is facilitated. In addition, since the dielectric ceramic for high frequency according to the present invention has a relative dielectric constant ε _r of 7.5 to 12.0, a high frequency circuit element having both features of improved workability and downsizing is provided. Becomes easier.

  Furthermore, since the dielectric ceramic for high frequency according to the present invention has an arithmetic average roughness Ra of 2 μm or less, it is difficult to be affected by the skin effect, and it is easy to provide a high frequency circuit element having a high unloaded Q value. . An example of such a high frequency circuit element is a coaxial dielectric resonator as shown in FIG. Here, a block in which a cylindrical through hole having a hole diameter of 3 mm is provided along the axial length direction in a block of a dielectric ceramic having an outer dimension of 10.6 mm × 10.6 mm × 12 mm (axial length), and the through hole is opened. Only one surface (open surface) of the dielectric ceramic is left as it is (ceramic surface), and a conductor film made of an Ag conductor is formed on the other surface of the dielectric ceramic and the inner surface of the through hole.

The reason for limiting the composition of the high frequency dielectric ceramic according to the present invention will be described. In the composition formula a (Sn, Ti) O ₂ —bMg ₂ SiO ₄ —cMgTi ₂ O ₅ —dMgSiO ₃ , if a is less than 4, the temperature coefficient τ _f of the resonance frequency is smaller than −30 ppm / ° C. (that is, the temperature The absolute value of the coefficient τ _f is larger than 30 ppm / ° C.), which is not preferable. When a exceeds 37, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. A more preferable range of a is 18 ≦ a ≦ 36. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If b is less than 34, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If b exceeds 92, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. A more preferable range of b is 34 ≦ b ≦ 68. Within this range, the absolute value of the temperature coefficient τ _f of the resonance frequency is 20 ppm / ° C. or less. If c is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. When c exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable. If d is less than 2, the temperature coefficient τ _f of the resonance frequency becomes smaller than −30 ppm / ° C. (that is, the absolute value of the temperature coefficient τ _f becomes larger than 30 ppm / ° C.), which is not preferable. If d exceeds 15, the relative dielectric constant ε _r becomes larger than 12.0, which is not preferable.

As shown in the examples described later, the resonance frequency f is obtained by appropriately changing the molar ratios a, b, c and d in the composition formula within the composition range in the high frequency dielectric ceramic of the present invention. The absolute value of the temperature coefficient τ _f is 30 ppm / ° C. or less, that is, a desired value in the range of 7.5 to 12.0 is achieved while the dielectric constant ε r is in the range of 7.5 to 12.0 while realizing a sufficiently large Q _m value in the range where τ _f is close to zero It is possible to adjust to.

  Further, in a high-frequency circuit element including a member made of a high-frequency dielectric ceramic, for example, a coaxial dielectric resonator including a 10.6 mm □ dielectric ceramic block shown in FIG. 3, the arithmetic average roughness of the surface of the dielectric ceramic block When the thickness Ra exceeds 2 μm, the no-load Q value is greatly reduced, for example, 1000 or less, which is not preferable.

An embodiment of the method for manufacturing a high frequency dielectric ceramic according to the present invention is as follows. A predetermined amount of starting materials of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ are wet mixed together with a solvent such as alcohol. Subsequently, after removing the solvent, the mixture is crushed until D50 of the particle size distribution is 2 μm or less. An example of the particle size distribution of the obtained powder is shown in FIG. An organic binder such as polyvinyl alcohol is added to the powder thus obtained, mixed and homogenized, dried, crushed, and pressure-molded (pressure 100 to 1000 kg / cm ² ). The obtained molded product is fired at 1200 to 1450 ° C. in an oxygen-containing gas atmosphere such as air, so that the arithmetic average roughness Ra of the surface is 2 μm or less and the surface arithmetic mean roughness Ra is 2 μm or less. Can be obtained. When the D50 of the particle size distribution after mixing and crushing of the above starting materials exceeds 2 μm, the arithmetic average roughness Ra of the sintered body tends to exceed 2 μm, which leads to an unloaded Q value of the dielectric ceramic for high frequency. It tends to decline.

As shown in the examples described below, equimolar amounts of SnO ₂ and TiO ₂ can be used. In this case, in particular, the generated phase (Sn, Ti) O ₂ is preferably (Sn _0.8 Ti _0.2 ) O ₂ .

  The high-frequency dielectric ceramic thus obtained can be used as a component for a high-frequency circuit element having good characteristics without further surface flattening, thus making it easy to manufacture and miniaturizing. A high-frequency circuit element having both the characteristics of the device is provided. However, it may be processed into an appropriate shape and size if necessary.

  The high frequency dielectric porcelain of the present invention is formed, for example, by forming a film or wiring made of a conductor such as silver or copper on the outside, thereby forming a coaxial dielectric resonator as shown in FIG. 3 or a coaxial type using the same. It can be used to construct a high-frequency circuit element such as a dielectric filter. The plate-shaped high frequency dielectric ceramic of the present invention can be used as a dielectric wiring board for various high frequency circuits by forming a conductor wiring such as silver or copper.

In addition to SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ , oxidation materials such as MgO and SiO ₂ are used as raw materials for Sn, Mg, Si, and Ti, which are elements constituting the high frequency dielectric ceramic of the present invention. In addition, nitrates, carbonates, hydroxides, chlorides, organometallic compounds, and the like that become oxides upon firing can also be used.

  The high-frequency dielectric ceramic according to the present invention includes O, Sn, Mg, Si, and Ti as constituent elements. For example, Ca, Ba, Zr, Ni, and Fe derived from impurities in pulverized balls and raw material powders. , Cr, P, Na, etc. may be mixed as impurities.

The high frequency dielectric ceramic of the present invention, as long as the low dielectric constant and a high Q _m value is determined, can be used as components of various high-frequency circuit device. One such example is a component member in a dielectric resonator-controlled microwave transmitter as shown in FIG. Other examples of the high-frequency circuit element in which the high-frequency dielectric ceramic of the present invention is used as a constituent member include planar high-frequency circuit elements as shown in FIGS. 6A to 6I, respectively. It is done.

  Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.

[Example 1] (first invention)
Predetermined amounts were weighed so that SnO ₂ was 4.8 mol%, TiO ₂ was 4.8 mol%, and Mg ₂ SiO ₄ was 90.5 mol% (see Table 1), and these were mixed with ethanol and ZrO ₂ balls in a ball mill. And wet mixed for 12 hours. Then, after removing the solution, it was crushed. Subsequently, an appropriate amount of polyvinyl alcohol (PVA) solution was added to the crushed material and dried, and then the pellets were formed into pellets having a diameter of 20 mm and a thickness of 10 mm, and baked at 1300 ° C. for 2 hours in an air atmosphere.

The high frequency dielectric ceramic composition (see Table 1) thus obtained was processed into a size of 16 mm in diameter and 8 mm in thickness, and then measured by a dielectric resonance method, and Q × f at a resonance frequency of 5 to 12 GHz. A value (ie, Q _m × f. Value), a relative dielectric constant ε _r , and a temperature coefficient τ _f of the resonance frequency were obtained. The results are shown in Table 1.

When the obtained high frequency dielectric ceramic composition was subjected to X-ray diffraction analysis, as shown in FIG. 1, tin titanate ((Sn _0.8 Ti _0.2 ) O ₂ ), forsterite (Mg ₂ SiO ₄ ), magnesium titanate (MgTi ₂ O ₅ ), and steatite (MgSiO ₃ ) were confirmed to be composed of crystal phases.

The obtained high-frequency dielectric ceramic composition was subjected to surface composition analysis by energy dispersive X-ray spectroscopy [EDS] _{. As a result,} tin titanate ((Sn _{0. 8} Ti _0.2 ) O ₂ ), forsterite (Mg ₂ SiO ₄ ), and magnesium titanate (MgTi ₂ O ₅ ) were confirmed. FIG. 2 shows the analysis result.

Also, spray granules were prepared by adding 2.75 wt% PVA, 1 wt% cellosol, and 1 wt% dispersant to 100 wt% of the dielectric ceramic composition for high frequency. Using this spray granule, it was molded so as to have a green density of 2.1 g / cm ³ , and then fired under an air atmosphere condition of 1300 ° C. × 2 hours. The obtained sintered body has a hole (through hole), and only one surface (open surface) where the hole opens is left as it is, and an Ag film electrode is formed on the other surface. A dielectric coaxial resonator as a high frequency dielectric porcelain electronic component as shown was fabricated. The coaxial resonator had a shaft length of 12 mm, an outer shape (a length of one side of a substantially rectangular open surface) of 10.6 mm, and a hole diameter of 3 mm.

  With respect to the obtained coaxial resonator, the unloaded Q value was evaluated at a resonance frequency of 2 GHz. As a result, the no-load Q value as a coaxial resonator was 1302. Thus, by using the dielectric ceramic composition for high frequency according to the present invention, a coaxial resonator having excellent high frequency characteristics was obtained.

[Examples 2 to 12] (First invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ is weighed so as to have the blending amounts shown in Table 1, and mixed, crushed and molded under the same conditions as in Example 1, and in an air atmosphere By firing at a temperature of 1200 to 1350 ° C. for 2 hours, a dielectric ceramic composition for high frequency was produced, and the characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 1 to 5] (first invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ is weighed so as to have the blending amounts shown in Table 2, and mixed, crushed and molded under the same conditions as in Example 1, and in an air atmosphere A dielectric porcelain composition was prepared by firing at a temperature of 1200 to 1350 ° C. for 2 hours, and the characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Example 13] (second invention)
A predetermined amount was weighed so that SnO ₂ was 4.8 mol%, TiO ₂ was 4.8 mol%, and Mg ₂ SiO ₄ was 90.5 mol% (see Table 3), and these were mixed with ethanol and ZrO ₂ balls into a ball mill. And wet mixed for 12 hours. Then, after removing the solution, it was calcined at 1100 ° C. for 2 hours and pulverized. Using this calcined powder as a starting material, 0.5 part by weight of MnO was added to 100 parts by weight of the calcined powder, and these were placed in a ball mill together with ethanol and ZrO ₂ balls and wet mixed for 12 hours. Thereafter, the solution was removed, and an appropriate amount of polyvinyl alcohol (PVA) solution was added and dried. Then, the pellet was formed into a pellet having a diameter of 20 mm and a thickness of 8.2 mm, and baked at 1250 ° C. for 2 hours in an air atmosphere.

  The relative density of the thus obtained high frequency dielectric ceramic (see Table 3) was measured using the Archimedes method and found to be 96%.

Further, this high frequency dielectric ceramic is processed into a size of 16.7 mm in diameter and 7.8 mm in thickness, and then measured by a dielectric resonance method to determine a Qf value (ie, Q _m) at a resonance frequency of 5.9 to 6.5 GHz. Xf, value), relative permittivity ε _r , and temperature coefficient τ _f of resonance frequency. The results are shown in Table 3.

When X-ray diffraction analysis was performed on the obtained dielectric ceramic for high frequency, as shown in FIG. 7, the main production phase was tin titanate ((Sn _0.8 Ti _0.2 ) O ₂ ), forsterite. It was confirmed that it was composed of crystal phases of (Mg ₂ SiO ₄ ), magnesium titanate (MgTi ₂ O ₅ ), and steatite (MgSiO ₃ ). Further, when X-ray fluorescence analysis was performed on the obtained high frequency dielectric ceramic, the presence of MnO was confirmed.

On the other hand, with respect to 100 parts by weight of the starting material powder, 0.5 part by weight of MnO is added as a sintering aid, and 2.75 parts by weight of PVA, 1 part by weight of cellosol, and 1 part by weight of a dispersant are added. Spray granules were prepared. Using this spray granule, the green density was molded to 2.3 g / cm ³ , and then fired under an air atmosphere condition of 1250 ° C. × 2 hours. A coaxial dielectric resonator as shown in FIG. 3 was fabricated using the high frequency dielectric ceramic thus obtained as a constituent member. The coaxial dielectric resonator had a shaft length of 12 mm, an outer shape (a length of one side of a substantially rectangular open surface) of 10.6 mm, and a hole diameter of 3 mm.

  The obtained coaxial dielectric resonator was evaluated for an unloaded Q value at a resonance frequency of 2 GHz. As a result, the unloaded Q value as a coaxial dielectric resonator was 1320. Thus, the coaxial dielectric resonator which has the outstanding high frequency characteristic was obtained by using the dielectric ceramic for high frequencies which concerns on this invention.

[Examples 14 to 25] (second invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ was weighed so as to have a mixing ratio shown in Table 3, mixed under the same conditions as in Example 13, calcined, and pulverized. Using this calcined powder as a starting material, a predetermined amount of MnO was weighed and mixed so as to have the blending amount shown in Table 3, and the binder was added and molded in the same manner as in Example 13, and in an air atmosphere As shown in Table 3, it was fired at a temperature of 1225 to 1300 ° C. for 2 hours to produce a high frequency dielectric ceramic, and its characteristics were evaluated in the same manner as in Example 13. The results are shown in Table 3. In addition, the “state” column in Table 3 and Table 4 to be described later indicates whether or not traces reacted with the floor plate in contact with firing at the time of manufacturing are visually recognized, and the notation of “good” is the floor plate. The sign “reacted with the floorboard” indicates that the trace that reacted with the floorboard was visually recognized.

[Comparative Examples 6 to 17] (second invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ was weighed so as to have a blending ratio shown in Table 4, mixed under the same conditions as in Example 13, calcined, and pulverized. Using this calcined powder as a starting material, a predetermined amount of MnO was weighed and mixed so that the blending amount shown in Table 4 was obtained, and the binder was added and molded in the same manner as in Example 13 to obtain a table in an air atmosphere. 4 was baked at a temperature of 1225 to 1300 ° C. for 2 hours to produce a high frequency dielectric ceramic, and its characteristics were evaluated in the same manner as in Example 13. The results are shown in Table 4. Comparative example 13 corresponds to the example of the first invention.

[Example 26] (Third Invention)
Predetermined amounts were weighed so that SnO ₂ was 4.8 mol%, TiO ₂ was 4.8 mol%, and Mg ₂ SiO ₄ was 90.5 mol% (see Table 5), and these were mixed with ethanol and ZrO ₂ balls into a ball mill. And wet mixed for 12 hours. Then, after removing the solution, it was crushed. The particle size distribution of the powder obtained by this crushing was as shown in FIG. 8 (D50 is shown in Table 5). An appropriate amount of a polyvinyl alcohol (PVA) solution was added to the powder and dried, and then formed into pellets having a diameter of 10 mm and a thickness of 3.5 mm, and baked at 1300 ° C. for 2 hours in an air atmosphere.

The high frequency dielectric porcelain thus obtained (see Table 5 for the generated phase) is processed into a size of 9.6 mm in diameter and 3.3 mm in thickness, and then measured by the dielectric resonance method to have a resonance frequency of 5.9-6. Q _m × f at 5 GHz. The value, the relative permittivity ε _r , and the temperature coefficient τ _f of the resonance frequency were obtained. The results are shown in Table 5.

  The arithmetic average roughness Ra of the surface of the high frequency dielectric ceramic obtained by the firing was measured. The results are shown in Table 5.

When X-ray diffraction analysis was performed on the obtained dielectric ceramic for high frequency, as shown in FIG. 9, tin titanate ((Sn _0.8 Ti _0.2 ) O ₂ ), forsterite (Mg ₂ SiO ₄ ), it was confirmed to be composed of crystal phases of magnesium titanate (MgTi ₂ O ₅ ) and steatite (MgSiO ₃ ).

On the other hand, 2.75 wt% PVA, 1 wt% cellosol, and 1 wt% dispersant were added to 100 wt% of the powder obtained by the above-mentioned crushing to produce spray granules. Using this spray granule, it was molded so as to have a green density of 2.1 g / cm ³ , and then fired under an air atmosphere condition of 1300 ° C. × 2 hours. A coaxial dielectric resonator as shown in FIG. 3 was fabricated using the high frequency dielectric ceramic thus obtained as a constituent member. The coaxial dielectric resonator had a shaft length of 12 mm, an outer shape (a length of one side of a substantially rectangular open surface) of 10.6 mm, and a hole diameter of 3 mm.

  The obtained coaxial dielectric resonator was evaluated for an unloaded Q value at a resonance frequency of 2 GHz. As a result, the unloaded Q value as a coaxial dielectric resonator was 1360. Thus, the coaxial dielectric resonator which has the outstanding high frequency characteristic was obtained by using the dielectric ceramic for high frequencies which concerns on this invention.

[Examples 27 to 36] (third invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ was weighed so as to have the blending ratio shown in Table 5, and mixed, crushed and molded under the same conditions as in Example 26. A high frequency dielectric ceramic was produced by firing at 1200 to 1350 ° C. for 2 hours, and the characteristics were evaluated in the same manner as in Example 26. The results are shown in Table 5.

[Comparative Examples 18 to 24] (third invention)
A predetermined amount of SnO ₂ , TiO ₂ , and Mg ₂ SiO ₄ was weighed so as to have the blending ratio shown in Table 6, and mixed, crushed and molded under the same conditions as in Example 26. A high frequency dielectric ceramic was produced by firing at 1200 to 1350 ° C. for 2 hours, and the characteristics were evaluated in the same manner as in Example 26. The results are shown in Table 6. Comparative example 21 and comparative example 22 correspond to the examples of the first invention.

  As described above, the high-frequency dielectric ceramic composition of the present invention can be used to produce a high-frequency dielectric ceramic electronic component such as a communication filter.

As described above, the dielectric ceramic for high frequency according to the present invention has a low dielectric constant and a high Q _m value and excellent temperature characteristics. Therefore, for example, an integrated circuit used in a high frequency region such as a microwave and a millimeter wave can be used. It is optimal as a constituent member of a high-frequency circuit element.

DESCRIPTION OF SYMBOLS 1 ... Coaxial dielectric resonator 2 ... Support member 3 ... Dielectric ceramic substrate 4 ... Strip conductor 5 ... Metal case H ... Electromagnetic field 6 ... Dielectric ceramic substrate 7 ... Strip conductor 8 ... Grounding conductor film 9 ... Plane high-frequency circuit

Claims (8)

A high frequency dielectric ceramic comprising a main component and an additive component,
The main component is represented by a composition formula a (Sn, Ti) O ₂ -bMg ₂ SiO ₄ -cMgTi ₂ O ₅ -dMgSiO ₃ , and a, b, c, and d (where a, b in the composition formula) , C, and d are in mol%) within the range of 4 ≦ a ≦ 37, 34 ≦ b ≦ 92, 2 ≦ c ≦ 15, and 2 ≦ d ≦ 15, where a + b + c + d = 100 A dielectric ceramic composition for high frequencies,
The additive component comprises MnO,
The additive component is added in an amount of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the main component,
The relative density is 95% or more,
The relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value is 50000 or more and the resonance frequency f. Temperature coefficient tau _f of a -30~ + 30ppm / ℃,
A high frequency dielectric ceramic. _{2. The} dielectric ceramic for high frequency according to claim 1, wherein the (Sn, Ti) O ₂ is (Sn _0.8 Ti _0.2 ) O ₂ . A method for producing a dielectric ceramic for high frequency according to claim 1 or 2 , wherein a predetermined amount of SnO ₂ , TiO ₂ and Mg ₂ SiO ₄ is mixed and calcined and then pulverized as a starting material, An organic binder is added to a powder obtained by adding 0.1 to 5.0 parts by weight of MnO as a sintering aid with respect to 100 parts by weight of the starting material, and is fired. Manufacturing method of dielectric ceramic for high frequency. A high-frequency circuit element comprising a member comprising the high-frequency dielectric ceramic according to claim 1 . Represented by the composition formula a (Sn, Ti) O ₂ —bMg ₂ SiO ₄ —cMgTi ₂ O ₅ —dMgSiO ₃ , and a, b, c, and d (where a, b, c, and d in the composition formula) in the range is the molar%) of 4 ≦ a ≦ 37,34 ≦ b ≦ 92,2 ≦ c ≦ 15, and 2 ≦ d ≦ 15, respectively, wherein a a + b + c + d = 100, obtained by calcining A high frequency dielectric ceramic composition,
The arithmetic average roughness Ra of the surface in the unprocessed state after firing is 2 μm or less,
The relative dielectric constant ε _r is 7.5 to 12.0, and Q _m × f. The value is 50000 or more and the resonance frequency f. Has a temperature coefficient τ _f of −30 to +30 ppm / ° C.
A high frequency dielectric ceramic.
The high frequency dielectric ceramic according to claim 5 , wherein the (Sn, Ti) O ₂ is (Sn _0.8 Ti _0.2 ) O ₂ . A method for producing a dielectric ceramic for high frequency according to claim 5 or 6 , wherein SnO ₂ , TiO ₂ and Mg ₂ SiO ₄ are used as starting materials, and a predetermined amount of these starting materials is used with a D50 of 2 μm in particle size distribution. A method for producing a dielectric ceramic for high frequency, characterized in that a binder is added to a powder obtained by mixing and pulverizing so as to form as follows, followed by firing. A high-frequency circuit element comprising a member comprising the high-frequency dielectric ceramic according to claim 5 .

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